Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 21. 2003. (Budapest, 2003)

Early Jurassic in the shallowest environments and short-looped terebratulids may have occupied deeper water niches. As SANDY'S (1995a) theory is based on Rhaetian and Pliensbachian data, the new Hettangian and Sinemurian results from Hungary are important to shed new light at this question. In case of the Hettangian Kardosrét Limestone fauna (Figure 5, left), 96% of the brachiopods belongs to terebratulids, from which 95% is the ratio of the shortlooped forms (92% of the specimens belongs to the genus Lobothyris and 67% belongs to the species Lobotlyris ovatissimaeformis). The ratio of rhynchonellids, spiriferinids and longlooped terebratulids is very small in this agitated shallow brachiopods 47 water environment. Thus, this Early Liassic fauna shows the typical composition of the Late Triassic shallow water fauna. The Kálvária-domb at Tata represents a deeper depositional environment in the Hettangian (Figure 5, right side). In this case 60% of the brachiopods belongs to the rhynchonellids, the ratio of spiriferinids is 10%, whereas, 30% of the specimens belongs to terebratulids, of which 10% is short-looped and 20% is long-looped. Sandy observed a similar taxonomic composition at the middle part of the Late Triassic outer shelf (dominated by rhynchonellids, spiriferinids and long-looped terebratulids). Figure 6 — Proportion of the brachiopod orders at the Lower Sinemurian localities of the Bakony Mts. The basin and basin-marginal Lower Sinemurian localities show quite different taxonomic compositions. In the basin material of the LxSkuti-domb (Figure 6, right), terebratulids dominate in the fauna (44%, of which 42% is long-looped). Rhynchonellids and spiriferinids occur in smaller ratio (29% and 27%, respectively). This composition is similar to SANDY's (1995a) Pliensbachian deepwater assemblages. At Som-hegy (Figure 6, left), situated at margin of basin and at the foot of a submarine horst, the taxonomic composition shows an atypically high ratio of rhynchonellids (79%). This high proportion is due to the predominance of genus Rhynchonellina, probably controlled by cold seep activity at the synseclimentary faults of the horst-graben structure. If the genus Khynchonellina (65%) is left out of consideration, as independent of depth conditions and controlled by the local cold-seeps, the composition of the remaining brachiopod fauna is the following: rhynchonellids (25%), spiriferinids (43%), long-looped terebratulids (28%) and short-looped terebratulids are only 4%. This taxonomic composition is also similar to SANDY's (1995a) Early Jurassic deep-water assemblages, but the high amount of cold-seep associated Khynchonellina specimens have changed the depth-dependent ratio of the brachiopod orders. Of course, it is possible that some other brachiopod species of this locality were also connected with coldseep activity. However, up to now only Rlynchonellina was mentioned as a cold-seep related taxon (e.g. SANDY 1995b; RUGGIEROTADDEI 1997). The four localities in the Eastern Gerecse are situated within the same basin (Pisznice Basin according to VÖRÖS & GALÁCZ 1998) (Figure 7). The proportion of rhynchonellids is nearly the same at all of the localities (between 43% and 46%). The ratio of spiriferinids is very low at Tölgyhát and Póckő (6% and 8%, respectively), but higher at Kisgerecse (19%) and Vöröshíd quarry (17%). Terebratulids occur in high proportion at Tölgyhát (46%) and Póckő (44%) but their ratio is smaller at Kisgerecse (36%) and Vöröshíd quarry (37%). The decrease of terebratulids